The present invention relates to a molecular and isotopic fractionning process, and to apparatus wherein said process may be carried out.
Hitherto several methods for separating molecular and isotopic mixtures are known, and particularly concerning isotopes and more specifically uranium; they are carried out in gaseous phase in appropriate devices by means of spreading or centrifugating or else through tuyeres.
The gaseous spread method is based on the speed difference in the gaseous fluid passage through a porous wall. This method has the disadvantage of requiring a high energy consumption and large plants.
In the gaseous-phase centrifugating process, fractionning is achieved through the centrifugal field which enriches the system in the heaviest component at the widest radial zone. In this case, however, besides the high energy consumption, expensive and complex equipments are required, and the centrifugal machine rotator must always hang within a magnetic field. Said centrifugal machine comprises a cylindric, thin-wall rotator rotating inside a shell at a speed close to 400 mts/sec. The gaseous feed is injected in the rotator near the center and the product and residue are continuously discharged through the upper and lower portions, respectively. The adequate design, equilibrating and maintenance of the rotator in this type of device presents a hard-to-solve problem.
The fractionnning process performed by means of tuyeres is based on diverting a gas stream which spreads throughout a curved wall. The thus created centrifugal field causes fractioning to take place. This process in practice requires a great number of micrometrical and highly accurate tuyeres for a given plant, with subsequent complications and high costs. In addition, a plant of this type requires great energy availability to recompress the gas which is spread in each separating step and counterbalance the losses produced by viscous friction. The development of this process is known to having achieved a diminution in the original costs, but cannot be exploited on a large scale.
French Pat. No. 75 32643 describes a device characterized by having on the side surface of a cylindric container a plurality of injection openings connecting the inside of said container with a pressured gaseous mixture source, and housing means for a first gaseous mixture fraction escaping through at least one extraction opening.